It’s common for psychologists to use the terms “self-control” and “cognitive control” interchangeably. Consider the introduction to a review paper published recently in Trends in Cognitive Sciences on whether our self-control is limited or not (I’ve added the emphases): “Whereas cognitive control relies on at least three separate (yet related) executive functions – task switching, working-memory, and inhibition – at its heart, self-control is most clearly related to inhibitory cognitive control …”

When scholars do make a distinction, they mostly use self-control to refer to the ability to delay immediate gratification in the service of a longer-term goal, whereas they use the term cognitive control to refer to the related ability to ignore distracting information or stimuli. Defined this way, do self-control and cognitive control essentially involve the same mental processes? According to a new study by Stefan Scherbaum at Technische Universität Dresden and his colleagues in Acta Psychologica, they do not.

Forty-eight student participants completed alternating trials of the Simon Test and “inter-temporal” decision making (i.e. deciding between immediate or more distant rewards). This was a mash up of a well-established cognitive control test and an established self-control test.

The Simon task, which taps cognitive control, required the participants to indicate as fast as possible the direction of an on-screen arrow, while ignoring the arrow’s screen location. On incongruent trials where the arrow’s direction and screen location are in opposition (e.g. a left-ward pointing arrow on the right side of the screen), it takes cognitive control to perform well at the task.

For the inter-temporal decisions, the students had to choose between smaller cash rewards now or larger cash rewards later (they were asked to pretend these were real decisions). It takes self-control to resist smaller immediate rewards for longer-term larger gain.

A critical phenomenon that occurs during the Simon Task is that while people are generally slower on incongruent trials, completing one incongruent trial leads to improved performance on a subsequent incongruent trial, as if one’s powers of cognitive control have been activated or engaged. Scherbaum and his colleagues’ ingenious idea was to see if this effect would spill over into the decision making trials. Would participants, after having their cognitive control activated by an incongruent Simon Task trial, show more self-control when making a financial decision immediately afterwards?

If cognitive control and self-control essentially involve the same cognitive processes, then the researchers should have found this spill-over effect between the two types of trial, but in fact there was no evidence for this in the results, not a hint of it. In a further analysis the researchers also couldn’t see any evidence of self-control processes, as measured by participants’ making more patient financial decisions, having any effect on their cognitive control, as measured by their subsequent Simon Task performance.

Of course this study isn’t conclusive. It’s possible that different measures of cognitive control and self-control might in future uncover some overlap. However, what the new findings do suggest is that, at least to a degree, the two constructs depend on different mental processes that operate independently.

The researchers concluded: “While both cognitive control and self-control may be observed when we control and steer our behavior toward the pursuit of long-term goals, they may depend on different underlying processes such as the avoidance of distraction – in the case of cognitive control – or resisting short-term temptations – in the case of self-control.”

One of the most contentious areas in psychology at present is the question of whether our willpower or self-control is a limited resource or not, as proposed by the theory of “ego-depletion“. This new paper may lead us to wonder whether confusion around the related concepts of self-control and cognitive control has contributed to disagreements and inconsistencies in the research into ego-depletion.

A greater understanding of the different mental processes that contribute to self-control and cognitive control might also contribute to better designed interventions for improving people’s focus, goal-planning and self-discipline.